A typical offset lithographic printing press has a plate cylinder upon which the negative of the text and illustrations to be printed are etched by a photographic and/or an electronic process. Dampening rollers apply a fountain solution to the plate cylinder which adheres to the plate cylinder except in the areas in which the text and illustrations are located.
Next, a series of form rollers, also known in the art as inking rollers, apply a layer of ink to the plate cylinder. The ink adheres to the plate cylinder only in the etched areas comprising the text and illustrations.
The plate cylinder then presses the inked text and illustrations onto a rubber blanket cylinder. An impression cylinder then presses a sheet of paper or other substrate to be printed against the blanket cylinder as the paper or other substrate passes between the blanket cylinder and the impression cylinder. The inked text and illustrations on the blanket cylinder are transferred onto the paper or other substrate to effect printing thereof.
Over time, ink, paper fiber, spray powder, and other contaminants build up in the fountain solution. These contaminants negatively impact print quality. Additionally, as the fountain solution degrades water adjustments are required. Eventually the fountain solution becomes so contaminated that it needs to be replaced. The present invention comprises a system for minimizing fountain solution contamination thereby extending the useful life of the fountain solution by a substantial period of time.
The fountain solution recycling system of the present invention utilizes a unique multi-stage separation technology and a recirculation pump to clean and restore the fountain solution. Removal of contaminants is achieved by processing the solution through three separate treatment stages resulting in a reusable, stabilized fountain solution. Components of the fountain solution which are consumed due to carry-off by the printing substrate and evaporation are replaced in the conventional manner.
Use of the fountain solution recycling system of the present invention easily and reliably reduces costs and improves productivity in an aspect of the commercial printing business that has traditionally been neglected. Simply extending the life of the fountain solution typically adds 1–2 hours of productivity per week per printing press because changing the fountain solution and cleaning the system are no longer required.
Additionally, by extending the life of the fountain solution waste disposal costs associated with fountain solution replacement are dramatically reduced. In those instances in which spent fountain solution is drained, use of the present invention greatly reduces the copper, zinc, ink, glycols, phosphates and suspended solids going into the drain thereby lessening the impact on the environment.